The project is designed to study the relationship between phospholipid metabolism and phagocytosis by normal and leukemic polymorphonuclear (PMN) leukocytes. Emphasis will be placed on the metabolism of phosphatidylcholine (PC), phosphatidylethonolamine (PE), and the phosphoinositides in leukemic cells at rest and during phagocytosis. It is planned to measure the labeling of phospholipids by Pi32, myo-(2H3)inositol, P32-labeled lysoPC and P32-labeled lysoPE in leukocytes. Isotope incorporation into each lipid will be measured by counting the intact lipids in a liquid scintillation counter, after the lipids are extracted and resolved by thin-layer paper chromatography. In order to ascertain whether the increased phospholipid synthesis during phagocytosis is associated with particle uptake or lysosomal enzyme extrusion, the response of leukocytes to colchicine, cyclic nucleotides, and cytochalasin B will be investigated. Kinetic studies of the effects of these agents on the labeling of phospholipids by radiotracers, particle uptake, and lysosomal enzyme release would demonstrate the relationship between phospholipid metabolism and phagocytic function of leukocytes. The enzymes involved in the metabolism of these phospholipids and the intracellular site of the phospholipid response will be examined by the technique of subcellular fractionation. This will illustrate the mechanisms by which phospholipid synthesis is increased during phagocytosis by PMN cells. It is planned to analyze the fatty acid compositions of the phospholipids in normal and leukemic cells by gas chromatography and thin-layer chromatography. The phagocytic function of leukocytes will also be examined by parallel assay of bacterial killing activity and phospholipase A2 activity.